Conversion of hydrocarbons



May 2591948 T. w. NELSON ErAL CONVERSION 0F HYDROCARBONS Filed Oct. 9, 1942 Patented May 25, 1948 UNITED STATES PATENT OFFICE coNvERsIoN 'or H'Ynno'oARsoNs Theodore W. Nelson, Woodbury, Henry D. Noll, Wenonah, and Thomas P. Simpson, Woodbury,

N. J., assignors to Socony-Vacuun Oil Company, Incorporated, a 'corporation of New York Ap'piieation octber 9, 1942, serial No. 461,444

6 Claims.

A This invention has to do with the conversion of petroleum hydrocarbons of gas oil boiling range toaviation fuels ofV exceptional quality.

Y There are several methods for the determination and expression of the anti-knock rating of aviation fuels. Typicalniethcds are those of Cooperative Fuel Research Committee commonly known as the CFR. Those of one kind, of which method AFD-71C is typical, compare the testedfuel and a standard vunder conditions of lean mixture where the tendency to knock `is most pronounced. A more recently adopted method compares under conditions more nearly related to maximum demandperformance. This latter, `the rich mixture anti-knock rating,`

method AFD-3C, sometimes called the supercharged aviation method is determined by comparisons of tested fuel and a reference fuel in the same engine, at the fuel-air ratio giving peak power on the reference fuel. The two methods are notcomparable, being measures of basically different operating characteristics. Two fuels of the saineeAFD-IC rating may be Widely different under AFD-3C rating. The AFD-3C rating method is intended to more closely reproduce actual operating conditions and reflect action of fuel when the engine is called upon for maximum power output.

. It is well known that aviation base stocks may be prepared by subjecting .petroleum material of ga's oil nature, boiling in the range 400-750 F. to catalytic cracking in vapor phase in the presen'ce of solid adsorptive catalytic material, and thenreprocessing the gasoline so produced under similar but more rigorous conditions, and separating from the product, material meeting the aviation boiling range specifications, namely with a 90% ASTM boiling point such that when the productis blended with alkylate or other agents,

the 1 0 v"octane blend meets existing specifications. i

While these materials form Vquite acceptable aviation'fuels, whenevaluated by the AFD-1C and methods, they are. less'valuable, i. e., Vrqiiir'e more alkylate, tetra ethyl lead, etc., to

2 be acceptable when measured bythe method; For example, a given product` of `two pass operation may be blended --40 ywith a certain alkylate andwithl cc, of lead tosmake a Vrating by AFD-1C, but would vhavean AFDfBC rating of only S-l-i-O, cc., that is a rating equal to reference fuel #1, 'plus 0.6 cc. lead, Where the present requirement to be met would be AFD-3C of VS-l-i- LO cc. The requirement could be met by using a 'blend of flQ% fuel and' 60%v alkylate, (alkylate in both cases lrating as AFD-3C* Aof `S1+3.0 cc., but fobviouslyrequiring more than twice as much alkylate Ato blend olf a 'given amount ofbasefuel.) .4

This invention 'is based upon the Isurprisiner discovery that by proper handling of lthe materials from second pass operation in a further catalytic cracking, base fuels of 'exceptionally high AFD-:3C rich-'mixturerating can 'be produced, and ithas for itspbject the provision of an 'op- Ie'rati'ng method whereby 'such production can be achieved, `leading kdirectly to viuels of markedly increased capability withfsimultaneous savings of alkylate and similarA materials.

In laccordance with 'this invention, materials from the scion'd ipass catalytic,crackingV of. @atv alytic gasoline, winch materials'are offhieher boiling 'point than 'aviation gasoline, Vmay befsubjected to third cracking to yield ja product within the aviation boilin'grange, which, with 4 icc. lead, will have 'an electiveLAFD-3C'irating of SLI-|16 cc. lead and'higher.` The process may be carried out. by'n'nrec'ycle third pass cracking Yoff the selected material, by recycling the same 'material tothe second pass operation in "addi'tion to thenormal "feed thereto, or byrecycle cracking to total consumption f4 the selected material alone in a third pass operation.

As an example of the surprising Yefficacy of this operaticmthe tabularidatahelpw showtherrcp- Acities, ofA aviation gasoline produced by taking the naphtha, heavier than gasoline, produced imm two passtreatment, and againpcrackine it. as compared .Withthe aviation gasoline produced by two pass operation. Y

Table I Produced by- Pmpertles of Aviano Gasohne Non-Recycle Crack- Second-Pass Processing of Second-Pass ing of First-Pass Gaso- Naphtha line Gravity, A. P. I 50.4-. 61.0. Acid Heat, F in 6.0. Accel. hr.) gum, Mgs./100 ca 6 9.0. Distillation ASTM, F.:

I. B. P- 99 102. Vol 129 133 507 Vnl 238 196. 90 D Vnl 283 277. E. P 317 306. Rec. Per cent Vol 98.5 98.0 Octane Rating AFD-1G:

cc. T. E. L.-

0 86 4 Y 79.6. 3 99 4 95.3. 4 IsJcane-lho cc. T. 98.7. 100 O. N. Blend (4 cc. T. E. L):

Per cent Alkylate Reqd 0 20. AFD-30 Rating S-1+6.0 cc. T. E. L.-- S-Z+1.5 cc. T. E. L.

Probably the most striking thing apparent from the above comparison of the two fuels is the AFD-3C rating of the two fuels in contrast to their AFD-1C rating. Both fuels, when mixed with 4 cc. of lead give fuels of about 100 octane rating. Yet, under rich mixture conditions, the second pass aviation product, with 4 cc. of lead and in an 80-20 mixture with alkylate, gives a rating of -only S-1+1.5 cc. while the third pass product of this invention, with 4 cc. lead, but without alkylate, has arating of S-1-l-6.0 cc. When total recycling is employed in the third pass operation, the aviation gasoline product, with 4 cc. lead has an AFD-3C rating of S-1| 10 The steps utilized in arriving at this product are as follows: First, a gas oil of 720 F. end point of Coastal-Mirando origin, was cracked in vapor phase in a static bed catalytic cracking lat a space velocity of 1.2 at 32 p. s, i. gauge and 830 F. to yield a first pass gasoline of about 400 F. end point. This cracking may be varied in temperature between about 800 F. and 900 F., and in pressure between 0 p. s. i. gauge and 75 or so p. s. i. gauge, and at space velocities of at least about 0.25, dependent upon the stock being handled, upon the activity of the catalyst, the method of handling-i. e., Whether static bed of catalyst or continuously renewed catalyst, etc., as is well known. The gasoline so produced was then reprocessed, in this instance being treated in a static bed, at 40 p. s. i. gauge and 835 F., and at a space velocity of 0.82, these conditions being appreciably more rigorous than those of the original. This second pass processing of gasoline boiling material will normally be conducted `within the same broad temperature and pressure ranges as cracking, but at conditions somewhat more rigorous than the corresponding cracking. The aviation gasoline boiling point product of this second'pass is that material described in the right hand column of Table I. The second pass product heavier than this, which was used as the charge in the third pass operation, and the following properties:

Second pass heavy naphtha Damnation ASTM, F.:

This material was cracked at a temperature of 850 F., pressure of 50 p. s. i. and space velocity of 1.0. Here, while being more rigorous than second pass conditions, the temperature and pressure will be within the same broad general ranges. Appropriate conditions for second pass operation and third pass operation both, like the rst pass operation, will vary somewhat for the activity of the catalyst and method of contacting catalyst, as do the rst pass operating conditions, but variations arising from the original charge stock will tend to be ironed out to a greater degree in these subsequent pass operations.

'I'he third pass operation may be conducted in several ways. The rst and simplest method is a single or once through operation upon the second pass heavy naphtha alone. This is the method used in the operation from which exemplary data was taken. Likewise a most highly anti-knock product can be gotten by a separate operation utilizing as fresh ch'arge the second pass heavy naphtha, and recycling to that operation the naphtha heavier than aviation cut produced therein. This operation, when carried out yas an ultimate recycle, i. e., recycling enough to consume al1 fresh charge and producing no side cut or drag in substantial amount, will give product of even higher rating than that shown. Another method for obtaining somewhat similar results consists of recycling the second pass heavy naphtha during the second pass processing, and deriving from that second pass operation, a product which combines the normal second pass aviation cut and the law'ation cut produced by recracking the second pass naphtha.

For a more complete understanding -ofV the invention reference is made to the accompanying drawing, which is illustrative only and wherein the single figure is a Vdiagrammatic flow sheet illustrating one arrangement of catalytic cracking and fractionating equipment wherein theprocess contemplated herein may be practiced.

In the drawing, numeral l indicates a `heater to which gas oil is charged through the inlet pipe 2. The heated vapors leaving the heater I under the temperature and pressure conditions heretofore yindicated are conducted through a conduit :tinto a catalytic reactor 4'Where the vapors'are cracked inv the' presence of a solid 4adsorptive catalytic material. f The catalyticallyexzr-acked product leaving the reactor Iv isA delivered through conduit Sinto a fractionating stepillustrated'by thefractionator 6 which is shown as being provided atits-top with a lgas outlet -'I and at its bottoni WithA an voutlet I?.Y through which residuum is'rejected from the system. The fractionator is also shown Vasloeing provided with a Vsuitably-- located plate or vtray section 9 anddraWeo-connectioiiiIII-I 0 through which a recycle material may, if'de'sir'ed; be recycled through Athe irst'pass Vcracking"operation practiced in Vheater I and reactor 4. Control of thisf'recycle is shown las being-effected by'valves II and I I.

The -irs't passnaphthahereinabove ,referred to iss'ho'wn as beingrwithdrawn from the fractionatoiithrough conduit I2. IThis rst pass naphtha which'v constitutes the charge -for the aforesaid second cracking operation carried out in heater I4 and catalytic reactor I5.is a fraction of the general nature of motor Ygasolineincluding matriallboilirigup tothe r'ange'400-ll50o F. 1 In the second pass cracking operation the first passfnaphtha vapors are conducted `from heater I4 to reactorrl through conduit I6, and inthis cracking operation, 'as aforesaid, the vapors are cracked inthe presence of a solid adsorptive catalytic material inreactor I5 under conditions inore rigorousthan those existent in the first cracking operation carriedout inheater I and reactor 4. v The -product of the second pass operation is sho'wnas 'being conducted from reactor I5 through conduit I'I to a fractionating step illust-rated by fractionator I8, which is shown as being provided with top and bottom outlet connections I9 and 2D for the discharge of gas and residue, respectively. The fractionating step illustrated by fractionator I3 is designed and operated so `as to provide a gasoline cut of end 'point suitable for aviation fuel (in the approximate range of BOO-#325 FJ. which cut is shown as being withdrawn from the fractionator I8` through conduit 2| as 2nd pass aviation gasoline. Also, as previously pointed out, this fractionating step is designedand operated so as to provide second pass heavy naphtha which is shown as being withdrawn from the iractionator I8 through conduit 22. This second pass heavy naphtha, as indicated by the typical specifications given hereinabove, is a fraction of relatively-narrow boiling range Vcomprising material heavier than the aviation gasoline cut` (Withdrawn-through conduit 2|) but containing no substantial quantity of material boiling above 488 F., and it is this relatively-narrow boiling range heavy naphtha fraction which is recracked toform the high-quality aviation gasoline hereinabove referred to.

As aforesaid, there are several alternative procedures for effecting this recracking or third `pass operation. The preferred procedure is to conduct the second pass heavy naphtha from conduit 22 through conduit 23 and valve 24 into a third cracking stage shown as being comprised of heater 25, conduit 26 and catalytic reactor 2'I. In thisthird pass crackin-g operation the second lpass heavy Anaphtha isl cracked in the presence of a solid adsorptive catalyticmaterial in reactor 2'I under conditions more rigorous than those existent in the second pass operation. The cracked products from this third cracking operation Vare conducted through conduit 52s ft'c a :fractionating step,- represeritedi by A fractionato'r 29,VA shown -as beingprovided Withf conventional gas and `residuurnuoiitlet's f29`g and 291i* Thi'siractionating s'te'p is' design-eiland operatedJsofas-to separate a'gasclinevfraction having anendipcint (in lthe s approximate range fof 30G-#3259. F.) s suit'- able for -use las aviation gasoline, which lfraction is shownA -as'lbeing .'withdrawn Vfrom 1 the' -1frac tionator-291through1conduit 30 -aslfrdpass-aviation gasoline. Itiis `fractionv'vhich has'been hereinabove. identified fas 'possessing I ithe'. flliig'hly desirable properties i of flo'w `Vacidsheat fardnfhih rich mixture performance. I fTheand pass-aviationgasol-inefand-the erdpas's aviation gasoline Vr'nay V:be lv'vithdravvnf-froinv the system s as independent. products throii'gh-'jvalve'd connections 2fI and 30'; rtheyniay beIDlended in: any suitablefmaiinereas through valvedccn'- duits -3 I- andi 32lto1fo'rm1t-he desired low acidlh'at, low endI point'. high rich -f'inixtu're- 'tanti-knock fuel. f Y' y --rn connection with .thetii u pass fieration 'just l ydesc'rilce `i,one kdesirable alternative4 or tionating step as tcx collectia -V`heavy` na'ph tin', which is -shovvn`v a's-being 'collected l iraetionatorl 29- Thisv thirdpas's-'lieavynaplitha is conducted Ithrough conduits Y 34J and Q35 (provided-With suitable valves-34' and'f35') to-the inlet. A23 o-i theheater -25 Where thefthird ipass 'heavynaphtha is Arecycled 'through thethird-'p'ass 4cracking operation with -the vsecondpass i 'heavy naphtha. v y

^ =Another alternative operation for effecting 'recracking of the second pass hea'vynaplitha "isto recycle same through the-second-passcracking operationcomprisedfof heater f4-and atalytic reactor- I5. For-the purpose cir carryingoutthls last-mentioned alternative the-conduit7252"V vis -800900 F. in the :presence'ofa solid adsorpti-ve catalytic material, segregatiirg '-fror'n the products of :suchv cracking operation 'a-rst passlnaphthacf the general nature of motor fgasolinefsiibjecting nsaid rst =passv naphtha to a second crack'higoperation under more rigorous conditions than 4those existent insaid lrstpass and lin the fpres- `ence of a. solid adsorptivecatalytic -materialgsegregating from the products of saidisecond-cracking: operation .a 'second `pass heavy naplithacomfprising material boiling/above:therange ot'aviation gasoline Abut containing no substantial quan- Atity of :material boiling-above `2188 Fi; subjecting said second pass naphtha to a third cracking operation in the presence of'asolid adsorptivecata- :lytic materialand Vunder conditions more rigorous than `those .existent in .-said seconder-aching operation, and segregatingl from vthe'lp'roduc't'o'f said third "cracking operation a gasoline Spr'o'duct fof aviation fuel end point.

2. A method for the production of aviation gas- Y oline which comprises the steps of: cracking a gas oil in vapor phase at temperatures in the range of BOO-900 F. in the presence of a solid adsorptive catalytic material, segregating from the products of such cracking operation a rst pass naphtha of the general nature of motor gasoline, subjecting said rst pass naphtha to a second cracking operation under more` rigorous conditions than those existent in said irst pass and in the presence of a solid adsorptive catalytic material, segregating from the products of said second cracking operation a second pass heavy naphtha comprising material boiling above the range of aviation gasoline but containing no substantial quantity of material boiling above 488 F., subjecting said second pass naphtha to a third cracking operation in the presence of a solid adsorptive catalytic material and under conditions more rigorous than those existent in said second cracking operation, segregating from the product of said third cracking operation a gasoline prod uct of aviation fuel end point and a third pass heavy naphtha; and recycling said third pass heavy naphtha to said third cracking operation.

3. A method for the production of aviation fuel of low end point, low acid heat and high rich mixture anti-knock rating which comprises the steps of cracking gas oil in vapor phase in the presence of a solid adsorptive catalytic material and segregating from the products of such cracking a rst pass naphtha including material having an end point not less than about 400 F. and not greater than about 450 F., subjecting said rst pass naphtha to cracking temperatures and pressures in the presence of solid adsorptive catalytic material, segregating from the products of said second pass a gasoline cut of end point suitable for aviation fuel and a second pass heavy naphtha comprising materials heavier than said gasoline cut :but containing no substantial quantity of materials boiling above about 488 F., and subjecting said second pass heavy naphtha to cracking temperatures and pressures in the presence of solid adsorptive catalytic material under cracking conditions more rigorous than the cracking conditions existent in said second pass operation to produce a gasoline product of aviation fuel end point and substantially high rich mixture rating.

4. A method for the production of aviation fuel of low end point, low acid heat and high rich mixture anti-knock rating which comprises the steps of cracking gas oil in vapor phase in the presence of a solid adsorptive catalytic material and segregating from the products of such cracking a first pass naphtha including material having an end point not less than about 400 F. and not greater than about 450 F., subjecting said iirst pass naphtha to cracking temperatures and pressures in the presence o solid adsorptive catalytic material under cracking conditions morerigorous than those existent in the rst pass operation, segregating from the products of said second pass a gasoline cut of end point suitable for aviation fuel and a second pass naphtha comprising materials heavier than said gasoline cut but containing no substantial quantity of materials boiling above about 488 F., subjecting said second pass heavy naphtha to recracking in the presence of solid adsorptive catalytic material under cracking conditions more rigorous than those existent in said second pass operation, and segregating from the products of the third pass operation a gasoline product of aviation fuel end point.

5. A method for the production of aviation gasoline which comprises cracking a petroleum hydrocarbon material of gas oil boiling range in Vapor phase in the presence of solid adsorptive catalytic material, segregating from the products of such cracking a rst pass naphtha of the general nature of motor gasoline, subjecting said rst pass naphtha to a second cracking operation in the presence of solid adsorptive catalytic material, segregating from the products of said second cracking operation a second pass heavy naphtha comprising material boiling above at least about 300 F. but containing no substantial quantity of material boiling above about 488 F., subjecting said second pass heavy naphtha to a third cracking operation in the presence of solid adsorptive catalytic material under the cracking conditions more rigorous than those existent in said second cracking operation, and segregating from the products of said third cracking operation a gasoline product of aviation fuel end point.

6. A method for the production of aviation gasoline which comprises cracking a petroleum hydrocarbon material of gas oil boiling range in vapor phase in the presence of solid adsorptive catalytic material, segregating from the products of such cracking a first pass naphtha of the general nature of motor gasoline, subjecting said iirst pass naphtha to a second cracking operation in the presence of solid adsorptive catalytic material, segregating from the products of said second cracking operation a second pass heavy naphtha comprising material boiling above at least about 300 F. but containing no substantial quantity of material boiling above about 488 F., subjecting said second pass heavy naphtha to a third cracking operation in the presence of solid adsorptive catalytic material under cracking conditions more rigorous than those existent in said second cracking operation, segregating from the products of said third cracking operation a gasoline product of aviation fuel end point and a heavy naphtha fraction, and recycling said third pass heavy naphtha fraction to said third cracking operation.

THEODORE W. NELSON. HENRY D. NOLL. THOMAS P. SIMPSON.

REFERENCES CITED The following references are of record in the le of this patent:

- UNITED STATES PATENTS Number Name Date 2,141,185 Houdry Dec. 27, 1938 2,254,553 Y Thomas Sept. 2, 1941 2,254,555 Thomas Sept. 2, 1941 2,267,766 Thomas et al Dec. 30, 1941 2,270,071 McGrew Jan. 13, 1942 2,294,584 Thomas Sept. 1, 1942 2,297,773 Kanhofer Oct. 6, 1942 2,300,032 Kassel Oct. 27, 1942 2,300,033 Kassel Oct. 27, 1942 2,303,107 Benedick Nov. 24, 1942 2,337,640 Burgin Dec. 28, 1943 2,345,128 Korpi Mar. 28, 1944 2,347,216 Peterkin Apr. 25, 1944 2,358,888 Thomas Sept. 26, 1944 2,361,138 Voorhies, Jr. Oct. 24, 1944 Certificate of Correction Patent No. 2,442,276. May 25, 1948. THEODORE W. NELSON ET AL. It is hereby certified that errors appear in the printed specication of the above numbered patent requiring correction as follows:

Column 3, line 22, in the table, last column thereof, for Z read 1; line 66, for

and the read had the; column 6, line 47, for 21 read Z1 and that the said Letters Patent should be read with these corrections therein that the Same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 1st day of March, A. D. 1949.

islam] THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

